During medical treatment, patients often require medication, blood, or fluids. The most efficient way of administering these substances is by depositing them directly into the patient's blood stream where the circulatory system quickly directs the substance to the target tissue or organ. Administering a substance directly into a patient's blood stream is most commonly accomplished by injection with a conventional needle and syringe. During the course of treatment, however, a patient will often require repeated or continuous doses of medications. It will be appreciated that repeated injections with a conventional needle can damage veins or arteries and cause significant discomfort to the patient.
When a patient requires repeated doses of medication or other substances, catheters are commonly employed. A catheter is a device that permits repeated and continuous administration of medication directly into a patient's blood stream, or other region of the body, without repeated injections. In one common configuration, catheters have a hollow tubular cannula and an adapter at the proximal end. The cannula of the catheter is inserted into the vein or artery of a patient while the catheter adapter remains outside the patient. The adapter permits repeated and continuous access to the patient's vascular system thus obviating the need for repeat injections.
In certain situations it is necessary to have access to the arteries of a patient. Generally this is necessary in order to monitor blood pressure and to take samples of arterial blood. In any event, in certain situations it is desirable to have the ability to repeatedly access an artery without making multiple needle punctures of the artery. In these situations it is often desirable to inert an arterial catheter.
There are many known devices and methods for introducing a catheter into a blood vessel. One such device uses an "inside-the-needle" configuration. As its name implies, this device has a catheter coaxially located within a hollow introducer needle. The patient's blood vessel is pierced with an introducer needle. Once the needle is within the patient's blood vessel, the catheter is manually advanced into the patient's blood vessel so that the desired length of the catheter has been inserted. The needle is then removed leaving the catheter in place. Thereafter, an adapter is attached to the proximal end of the catheter so that medication or other substances may be administered.
Another device used to introduce a catheter into a patient's blood vessel also uses an introducer needle to penetrate the blood vessel but in an "over-the-needle" configuration. In this arrangement, the catheter is coaxially placed over the needle. Once the needle is within the patient's blood vessel, the catheter is advanced over the introducer needle until the desired length of the catheter has been inserted. The needle is simultaneously withdrawn and discarded leaving the catheter in place. Because the catheter is located over the needle, an adapter need not be attached to the catheter after placement of the catheter in the blood vessel, but can be attached to the catheter prior to placement.
It will be appreciated that for maximum comfort to the patient, catheters should be constructed of a flexible pliable material. The more pliable the material, however, the more difficult it is to insert the catheter into the blood vessel. The catheter has a tendency to kink making its insertion difficult, and in many cases impossible. This is especially true for catheters that will be placed in an artery. As a result, vascular catheters typically employ a thin wire called a guide wire which can be advanced into the artery to provide a path for the catheter to follow while the catheter is positioned within the blood vessel.
One such catheter uses an introducer needle to penetrate the patient's artery. Once in place, a guide wire which is disposed within the introducer needle is manually advanced into the artery. The catheter is then detached and advanced from the introducer needle along the guide wire which guides the catheter within the artery. The introducer needle and the guide wire are then removed leaving the catheter in place.
Unfortunately, this device and method compromise stability by requiring the clinician to hold the catheter unit with one hand while the guide wire is manually advanced with the other. While the guide wire is being manually advanced, the needle within the artery is subject to movement making it difficult to steadily insert the guide wire.
Several automatic and semiautomatic devices and methods for advancing the guide wire are known in the art. One such device requires the clinician to carefully pierce the patient's skin with the introducer needle. Once the skin is punctured, but before the introducer needle pierces the blood vessel, a vacuum is created by manually extending a plunger or similar apparatus. Subsequently, the introducer needle is advanced further until the blood vessel is penetrated. Upon penetration, the vacuum in the chamber is broken and the guide wire is advanced by one of several different mechanisms. Alternatively, once the vacuum is broken and blood is visible in the chamber, the operator can manually initiate the guide wire advance mechanism.
Like the manual devices, these automatic and semiautomatic devices require the clinician to steadily hold the catheter unit with one hand while the plunger is extended to create a vacuum. In addition, these devices require great skill on the part of the clinician. If the blood vessel is penetrated before a vacuum is created, the guide wire will not automatically advance. Moreover, if the guide wire fails to properly advance neither the automatic nor the semiautomatic mechanisms permit the guide wire advance mechanism to be reset and reinitiated.
It will be appreciated that it would be an advancement in the art to provide a vascular access device that automatically advances a guide wire into a blood vessel. It would be a further advancement in the art if the guide wire could be advanced at a steady and a consistent rate and the device reset if necessary. It would be yet another advancement in the art if the flexible wire could be advanced with one hand without requiring the operator to remove one hand from the device.
Such a vascular access device is disclosed and claimed herein.